The top court in the Republic has ruled that life sentences may be imposed in rape cases in exceptional circumstances even if there is a guilty plea.
The Supreme Court judgment clarified the law on sentencing in such cases.
Mr Justice Nicholas Kearns said the fact of a guilty plea did not mean there must be a reduction in sentence.
He was giving the unanimous judgment of the five-judge court in appeals by two men against life sentences imposed for rape offences.
One man, a former soldier in his 50s had pleaded guilty to 20 counts of sexual offences over an 11-year period against two of his daughters and four of his nieces when they were children.
The second man, a farmer from the west of Ireland, admitted 10 sample charges of rape and two of sexual assault against four of his daughters between 1976 and 1996.
"It is impossible to conceive of a greater breach of parental reponsibility than occurred in these cases," Justice Kearns said.
He said judges should always take account of mitigating factors such as guilty pleas when passing sentence.
However, he said this did not mean there should always be a reduced sentence.
Justice Kearns said where exceptional circumstances resulted in a maximum sentence even with a guilty plea, those circumstances should be clearly identified.